Microneedle patches for transdermal delivery

ABSTRACT

Embodiment provided herein are directed to microneedle patches for agent application on a mammal skin. The microneedle patch may comprise a patch scaffold having a surface, and a plurality of microneedles disposed on the surface. Each of the microneedles may be capable of piercing the skin 50 μm to 1000 μm deep, and comprises a composite material comprising polyvinylpyrrolidone (PVP) and one or more additional copolymers selected from the group consisting of maltose, leucine, and dileucine.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/997,412, filed Jun. 4, 2018, which claims the benefit under 35 U.S.C.§ 119 (e) of the U.S. Provisional Application Ser. No. 62/515,426 ,filed Jun. 5, 2017, the contents of which are incorporated by referencein its entirety into the present disclosure.

FIELD OF THE INVENTION

The invention relates generally to transdermal therapies, and moreparticularly to a microneedle patch for transdermal application of anagent to mammalian skin.

BACKGROUND

Many agents (e.g. cosmetic preparations, chemicals, drugs, vaccines,etc.) may cause mild to severe allergic reactions including contactdermatitis in people. If a person suspects a particular agent isresponsible for his/her contact dermatitis, a patch test may be utilizedto assess the existence of a contact allergy to said agent. Patch testsare simple in concept, and generally comprise a sheet of material coatedwith the agent to be tested (e.g., the suspected allergen). The patch isapplied to the person's skin to introduce the suspected allergen to theimmune system of the patient. After removal of the patch, the presenceof an allergic reaction at the application site on the skin may bemacroscopically determined. Use of such patch tests, however, isassociated with several disadvantages. For instance, the patch test mayneed to be applied to the person's skin for a long period of time toallow the allergen to diffuse into the skin across the strong, hornyexterior thereof (i.e., the stratum corneum). Moreover, there are oftenissues with accuracy in macroscopically determining the degree to whichan allergic response occurs at the application site of the allergen.

Intradermal injection of a suspected allergen via a hypodermic needle isanother method commonly used to deliver the antigen to a person's skin.However, use of hypodermic needles is painful and inconvenient forself-administration. Further, the manual insertion of the hypodermicneedle may be difficult to control, thus making targeted delivery of theallergen to specific sites within the skin difficult.

Microneedle patches (MNPs) represent a recent, non-invasive transdermaldelivery system for suspected allergens. The MNPs typically comprise apedestal to which microneedles containing an allergen are attached. Themicroneedles are configured to pierce the skin, and subsequentlydissolve upon insertion into the skin for the transdermal delivery ofthe allergen. Such dissolving microneedles may be less prone to breakingin vivo as compared to conventional silicon and metal needles.Microneedles comprised of polyvinylpyrrolidone (PVP) are often used forthe transdermal delivery of allergens.

The current MNPs are also associated with several limitations whichhinder their clinical application. For instance, the dissolvingmicroneedles have strict mechanical performance requirements. Themicroneedles need sufficient mechanical strength to perforate thestratum corneum. Incomplete penetration of needles into the skin leadsto an ineffective delivery of the allergen thereto and allergen wastage.Recent studies have shown significant variation in skin penetrationacross current, dissolving microneedles, which may be fabricated fromdiverse biomaterials. Pure PVP lacks sufficient biocompatibility, andthus is not an effective biomaterial for use in microneedles. Moreover,the low solubility of PVP also reduces the allergen release rate.

There is therefore a need for an improved device for the transdermaldelivery of an agent to mammalian skin, and which overcome thelimitations and disadvantages associated with the use of current patchtests, hypodermic needles, and MNPs.

SUMMARY

The present disclosure provides microneedle patches useful for safe andeffective delivery of agent to the skin of a subject. The agent may be asuspected allergen or a pharmaceutically or cosmetically effectiveagent.

Accordingly, in one embodiment, provided herein is a microneedle patchfor agent application on a mammal skin, where the microneedle patchcomprises a patch scaffold having a surface, and a plurality ofmicroneedles disposed on the surface. Each of the microneedles iscapable of piercing the skin 50 μm to 1000 μm deep and comprises acomposite material comprising polyvinylpyrrolidone (PVP) and one or moreadditional copolymers selected from the group consisting of maltose,leucine, and dileucine.

In some embodiments, each of the microneedles of the microneedle patchfurther comprises an agent. In some embodiments, each of themicroneedles is configured to dissolve and thereby deliver the agent tothe mammal upon application on the skin.

In some embodiments, at least two of the microneedles comprise differentagents.

In some embodiments, the agent is a cosmetic preparation or apharmaceutical preparation. In some embodiments, the patch is providedas a facial mask or a portion of the facial mask.

In some embodiments, the agent is uniformly disposed within thecomposite material of each microneedle.

In some embodiments, each of the microneedles comprises a tip portionproximate a tip of the microneedle and a stem portion that is furtherdistal from the tip. In some embodiments, the agent is not present inthe stem portion of each microneedle, or is present at the stem portionat a lower concentration than in the tip portion of each microneedle. Insome embodiments, the composite material is present at the tip portionat a lower concentration than in the stem portion.

In some embodiments, each of the microneedles comprises a plurality oflayers and each of the layers comprises alternately higher and lowerconcentrations of the agent.

In some embodiments, the agent is coated on at least a portion of anouter surface of the composite material of each microneedle.

In some embodiments, the microneedle patch further comprises a pedestalon the surface for adhesion to the skin.

In some embodiments, at least one of the one or more additionalcopolymers of the composite material is maltose. In some embodiments,the one or more additional copolymers of the composite material comprisemaltose, leucine, and dileucine.

In some embodiments, the composite material comprises about 70-90 wt. %PVP.

In some embodiments, each of the microneedles comprises a substantiallypyramidal shape.

In some embodiments, the microneedle patch further comprises a sensorcoupled to the patch scaffold and proximate each of the microneedles. Insome embodiments, the sensor is an image sensor or a thermal sensor.

Also provided herein, in one embodiment, is a method for determining animmune response in a mammal skin, where the method comprises: applying amicroneedle patch as described herein; and determining, via at least onesensor operatively coupled to the microneedle patch, whether the agentdelivered to the mammal from each of the microneedles induces an immuneresponse in the skin thereof. In some embodiments, the sensor utilizedin this method comprises an image sensor or a thermal sensor.

Also provided herein, in one embodiment, is a method for delivering acosmetic or pharmaceutical agent to a mammal skin, the method comprisingapplying the microneedle patch on the skin and allowing the cosmetic orpharmaceutical agent of the patch to be delivered to the skin.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred and non-limiting embodiments of the invention may be morereadily understood by referring to the accompanying drawings in which:

FIGS. 1A-1B depict isometric and side views, respectively, of amicroneedle patch comprising a plurality of microneedles on a surface ofa scaffold, according to one embodiment.

FIG. 2 depicts an isometric view of a microneedle patch comprisingdiscrete areas of microneedles, according to one embodiment.

FIG. 3 depicts a microneedle patch applied to mammalian skin, accordingto one embodiment.

FIGS. 4A-4E depict side view of a microneedle patch comprising aplurality of microneedles and an agent associated therewith, accordingto various embodiments.

FIGS. 5A-5B depict a side view and top view, respectively, of amicroneedle patch comprising a detector device configured to detect anallergic response, according to various embodiments.

FIG. 6 depicts a mold for preparation of a microneedle patch, accordingto one embodiment.

FIGS. 7A-7D depicts use of a microneedle patch in a mouse model,according to one embodiment.

DETAILED DESCRIPTION

Specific, non-limiting embodiments of the present invention will now bedescribed with reference to the figures, in which reference numeralsdenoting like features are labeled similarly. It should be understoodthat particular features and aspects of any embodiment disclosed hereinmay be used and/or combined with particular features and aspects of anyother embodiment disclosed herein. It should also be understood thatsuch embodiments are by way of example and are merely illustrative ofbut a small number of embodiments within the scope of the presentinvention. Various changes and modifications obvious to one skilled inthe art to which the present invention pertains are deemed to be withinthe spirit, scope and contemplation of the present invention as furtherdefined in the appended claims.

Unless the context requires otherwise, throughout the presentspecification and claims, the word “comprise” and variations thereof,such as, “comprises” and “comprising” are to be construed in an open,inclusive sense, that is as “including, but not limited to”. The use ofall examples, illustrations, and/or exemplary language (“e.g.”, “suchas”, etc.) herein does not impose a limitation on the scope of theinvention unless otherwise specified. Furthermore, recitation of numericranges of values throughout the specification is intended to serve as ashorthand notation of referring individually to each separate valuefalling within the range inclusive of the values defining the range, andeach separate value is incorporated in the specification as it wereindividually recited herein. Additionally, the singular forms “a”, “an”and “the” include plural referents unless the context clearly dictatesotherwise.

As discussed previously, patch testing is commonly used to identifyagents that a person's skin is allergic to. However, conventional patchtesting usually takes a long period of time, may result in inaccuratecharacterization of the degree of the allergic response, and isexpensive. Intradermal injection of an agent via a hypodermic needle isanother method commonly used to assess a person's response to saidagent; yet, use of hypodermic needles is often painful, difficult tocontrol, and inconvenient for self-administration. Moreover,conventional microneedle patches for transdermal delivery of an agentvary widely in their ability to penetrate mammalian skin, degree ofbiocompatibility, and ability to control the release of the agent.

Embodiments described herein are directed to a simple, inexpensive, andnovel microneedle patch for diagnosis of allergies to an agent. Inparticular, this microneedle patch provides a safe and easy way todeliver an agent (or agents) to the dermal layers of a person's skin.The microneedle patch may comprise a plurality of microneedles coupledto a surface of a scaffold (which may also be referred to herein as a“patch scaffold” or “pedestal”). The microneedles and scaffold may eachbe fabricated using polyvinylpyrrolidone (PVP) and one or moreadditional copolymers selected from the group consisting of maltose,leucine, and dileucine. The microneedles may additional comprise anagent disposed therein and/or coated thereon.

Use of the novel microneedle patch, as disclosed herein, may involvepressing the microneedle patch to a person's skin such that each of themicroneedles loaded with an agent pierces the skin. In some embodiments,the microneedles may have dimensions so as to pierce the skin about 50μm to about 1000 μm deep. The biocompatible composite material of themicroneedles dissolves upon insertion into the skin, thereby deliveringthe agent at a precise, controlled location within the dermal layers ofthe skin. The location of the agent within each microneedle may also betailored according to the methods disclosed herein, thereby allowing forcontrolled rates of agent release.

If the person being tested has an allergic response to an agent presentin the microneedles, the skin will respond rapidly, such as by anincrease in temperature. The “hot spots” (e.g., areas of increasedtemperature) caused by allergic responses may be detected by a sensor,such as a thermal or image sensor. For instance, in one embodiment, aninfrared (IR) image can be captured following the microneedle injectionto identify the hot spots. By loading at least one agent into themicroneedle in an array, a whole library of agents may be tested in asingle assay.

In some embodiments, the microneedle patch, as disclosed herein, may beuseful for testing a person's response to a cosmetic or preparation.Cosmetic preparations encompasses a heterogeneous group of often complexproducts. The ingredients in the cosmetic preparations often includeactive materials as well as other various natural and/or syntheticexcipients, such as preservatives, buffers, matrix components andfragrances. Such combination of active materials and excipients maycause mild to severe allergic reactions, such as contact dermatitis inmany people, and particularly immunocompromised people. The complexityof the allergic reactions becomes multifaceted when considering allegednatural topical formulations or cosmetics with more complicatedformulations. It is therefore beneficial to rigorously test cosmeticpreparations prior to their potential application since they not onlyencompass a wide range of ingredients, but are also formulated toproduce a wide range of products. The microneedle patch, as disclosedherein, is particularly suited for such use.

The microneedle patch can also be used to delivery agents to a skin, forcosmetic or pharmaceutical purposes. In this respect, the patch can beprovided in the form of a facial mask (or part of a facial mask), forexample. The cosmetic or pharmaceutical agents packaged in themicroneedle patch can be delivered into the skin, rendering desiredeffects on the skin. The cosmetic or pharmaceutical agents include,without limitation, agents capable of improving the look, nutrition, orhealth of the skin or ameliorating a condition or disease of the skin.

Referring now to FIGS. 1A-1B, an isometric and side view, respectively,of an exemplary microneedle patch 100 is shown in accordance with oneembodiment. The microneedle patch 100 may be implemented in combinationwith other devices/features/components described herein, such as thosedescribed with reference to other embodiments and FIGS. The microneedlepatch 100 may also be used in various applications and/or inpermutations, which may or may not be noted in the illustrativeembodiments described herein. For instance, the microneedle patch 100may include more or less features/components than those shown in FIG. 1,in some embodiments. Moreover, the microneedle patch 100 is not limitedto the size, shape, number of components, etc. specifically shown inFIG. 1.

As shown in FIGS. 1A-1B, the microneedle patch 100 comprises a pluralityof microneedles 102 disposed on a surface 104 of a scaffold 106. Eachmicroneedle comprises a base/stem portion 108 located proximate to thebase of the microneedle 102, where the base refers to the point ofattachment of the microneedle to the surface 104 of the scaffold. Eachmicroneedle 102 also comprises a tip portion 110 located proximate tothe tip of the microneedle 102 and further located distal to thebase/stem portion 108.

The number of microneedles 102 disposed on the surface of the scaffold106 may be selected based on a desired application. In some embodiments,the microneedle patch 100 may include at least 1, at least 2, at least3, at least 4, at least 5, at least 6, at least 7, at least 8, at least9, at least 10, at least 12, at least 14, at least 16, at least 18, atleast 20, at least 22, at least 24, at least 26, at least 28, at least30, at least 32, at least 34, at least 36, at least 38, at least 40,etc. microneedles 102. In some embodiments, the number of microneedles102 may be in a range including and between any two of the following: 1microneedle, 2 microneedles, 3 microneedles, 4 microneedles, 5microneedles, 6 microneedles, 7 microneedles, 8 microneedles, 9microneedles, 10 microneedles, 11 microneedles, 12 microneedles, 13microneedles, 14 microneedles, 15 microneedles, 16 microneedles, 17microneedles, 18 microneedles, 19 microneedles, 20 microneedles, 21microneedles, 22 microneedles, 23 microneedles, 24 microneedles, 25microneedles, 26 microneedles, 27 microneedles, 28 microneedles, 29microneedles, 30 microneedles, 31 microneedles, 32 microneedles, 34microneedles, 35 microneedles, 36 microneedles, 37 microneedles, 38microneedles, 39 microneedles, 40 microneedles, 45 microneedles, 50microneedles, 60 microneedles, 65 microneedles, 70 microneedles, 75microneedles, 80 microneedles, 85 microneedles, 90 microneedles, 95microneedles, 100 microneedles, 150 microneedles, 200 microneedles, 250microneedles, 300 microneedles, 350 microneedles, 400 microneedles, 450microneedles, 500 microneedles, 600 microneedles, 700 microneedles, 800microneedles, 900 microneedles, 1000 microneedles, 1200 microneedles,1400 microneedles, 1600 microneedles, 1800 microneedles, and 2000microneedles. In one embodiment, the microneedle patch 100 comprisesabout 24 microneedles 102.

In some embodiments, the microneedle patch 100 comprises a density ofabout 25 microneedles to about 625 microneedles per cm². In someembodiments, density of the microneedles may be in a range including andbetween any two of the following: 25/cm², 50/cm², 75/cm², 100/cm²,125/cm², 150/cm², 175/cm², 200/cm², 225/cm², 250/cm², 275/cm², 300/cm²,325/cm², 350/cm², 375/cm², 400/cm², 425/cm², 450/cm², 475/cm², 500/cm²,525/cm², 550/cm², 575/cm², 600/cm², and 625/cm².

In some embodiments, the microneedle patch 100 may comprise from 1 to 50rows, 1 to 40 rows, 1 to 30 rows, 1 to 20 rows, 1 to 10 rows, 1 to 9rows, 1 to 8 rows, 1 to 7 rows, 1 to 6 rows, 1 to 5 rows, 1 to 4 rows, 1to 3 rows, 1 to 2 rows, or 1 row of microneedles 102. Each row mayfurther comprise from 1 to 50 microneedles, from 1 to 40 microneedles,from 1 to 30 microneedles, from 1 to 20 microneedles, from 1 to 10microneedles, from 1 to 9 microneedles, from 1 to 8 microneedles, from 1to 7 microneedles, from 1 to 6 microneedles, from 1 to 5 microneedles,from 1 to 4 microneedles, from 1 to 3 microneedles, from 1 to 2microneedles, or 1 microneedle.

In some embodiments, the spacing, s₁, between the microneedles 102 in arow may be in a range from about 100 to about 1000 μm. In someembodiments, the spacing, s₁, between the microneedles 102 in a row maybe in a range including and between any two of the following: 100 μm,125 μm, 150 μm, 175 μm, 200 μm, 225 μm, 250 μm, 275 μm, 300 μm, 325 μm,350 μm, 375 μm, 400 μm, 425 μm, 450 μm, 475 μm, 500 μm, 525 μm, 550 μm,575 μm, 600 μm, 725 μm, 750 μm, 775 μm, 800 μm, 925 μm, 950 μm, 975 μm,and 1000 μm. In some embodiments, the spacing, s₁, between themicroneedles 102 in at least one row, a plurality of the rows, or eachrow may be about equal. In other embodiments, the spacing, s₁, betweenthe microneedles 102 in one row may be different than the spacingbetween the microneedles 102 in at least another row.

In some embodiments, the spacing, s₂, between at least two rows may bein a range from about 100 to about 1000 μm. In some embodiments, thespacing, s₂, between at least two rows may be in a range including andbetween any two of the following: 100 μm, 125 μm, 150 μm, 175 μm, 200μm, 225 μm, 250 μm, 275 μm, 300 μm, 325 μm, 350 μm, 375 μm, 400 μm, 425μm, 450 μm, 475 μm, 500 μm, 525 μm, 550 μm, 575 μm, 600 μm, 725 μm, 750μm, 775 μm, 800 μm, 925 μm, 950 μm, 975 μm, and 1000 μm. In someembodiments, the spacing, s₂, between each row may be about equal. Inother embodiment, the spacing, s₂, between the rows may be different.

In some embodiments, the microneedles 102 may be spaced uniformly (e.g.,at approximately equal intervals) on the surface of the scaffold 106.However, in other embodiments, e.g., as shown in the isometric view ofFIG. 2, the microneedle patch 100 may comprise two or more discreteareas 202, each of which comprises a plurality of microneedles 102. Inone such exemplary embodiment, the spacing, s₃, between each discretearea 202 may be about uniform (equal), and the spacing, s₄, between eachmicroneedle 102 in a particular discrete area 202 may be about uniform(equal), provided that s₃ is about equal to or greater than s₄.

The microneedles 102, e.g., as shown in FIGS. 1A-1B and 2, may comprisea substantially pyramidal or conical shape. Others microneedle shapesmay be suitable as would become apparent to one skilled in the art uponreading the present disclosure. For instance, in one embodiment, eachmicroneedle 102 may comprise a substantially cylindrical shape towardsthe base/stem portion 108 thereof that transitions to a substantiallypyramidal shape (e.g., a pointed portion) near the tip portion 110thereof. Moreover, the microneedles 102 are not limited to sharp pointedneedles, and may thus include blunt tips.

In some embodiments, the microneedles 102 may each have a maximum length(height, h_(n)) ranging from about 20 μm to about 1000 μm, preferably ina range from about 50 μm to about 1000 μm, and more preferably in arange from about 100 μm to about 1000 μm. In some embodiments, themicroneedles 102 may each have a maximum width, w_(n), ranging fromabout 10 μm to about 500 μm. In some embodiments, the microneedles 102may each have a high aspect ratio ranging from about 1:1 to 20:1, wherethe aspect ratio refers to the ratio of a microneedle's maximum length(height, h_(n)) relative to its maximum width.

In some embodiments, the microneedles 102 are configured to pierce theskin for the percutaneous administration of an agent. In particularembodiments, the microneedles are configured to piece the skin at adepth of about 50 μm to 1000 μm. FIG. 3 provides an exemplary embodimentof a microneedle patch 100 piercing mammalian (e.g., human) skin 300 toreach the dermis layer thereof is shown in FIG. 3. As shown in FIG. 3,the skin 300 comprises the following layers: stratum corneum 302 at adepth greater than 0 μm to about 20 μm); epidermis 304 at a depth fromabout 20 μm to about 100 μm; dermis 306 at a depth from about 100 μm toabout 1000 μm, and subcutis (hypodermis) 308 at a depth greater thanabout 1000 μm. The scaffold 104 of the microneedle patch may preferablycontact (and temporarily and removably adhere to) the outermost layer ofthe skin 300 (e.g., the stratum corneum 302), while the microneedles 102pierce the skin 300 such that the tips of said microneedles 102 arepositioned within (and do not extend deeper than) the dermis layer 306of the skin 300.

The microneedles 102, e.g., as shown in FIGS. 1A-1B, 2, and 3, are eachcomprised of a composite material. Additionally, the microneedles 102may each comprise an agent disposed within and/or coated on at least aportion of the composite material.

In some embodiments, the composite material of each of the microneedles102 is configured to dissolve after a predetermined period of time afterinsertion into mammalian skin, and thereby deliver the agent thereto. Insome embodiments, the composite material is biocompatible and/orbiodegradable. In some embodiments, the composite material comprisespolymer components that are approved by the Federal Drug Administration(FDA) and/or are GRAS (generally recognized as safe) polymers.

In some embodiments, the composite material comprisespolyvinylpyrrolidone (PVP) and one or more additional copolymersselected from the group consisting of maltose, leucine, and dileucine.In one embodiment, the composite material comprises at least PVP andmaltose. In one embodiment, the composite material comprises PVP,maltose, and one or more additional copolymer components selected fromleucine and dileucine. In one embodiment, the composite materialcomprises at least PVP, maltose, and leucine. In one embodiment, thecomposite material comprises at least PVP, maltose, and dileucine. Inone embodiment, the composite material comprises PVP, maltose, leucine,and dileucine.

In some embodiments, the composite material comprises about 50 to about90 wt. %, and more preferably about 70 to about 85 wt. %, PVP. In oneembodiment, the composite material comprises about 70 wt. % PVP. In oneembodiment, the composite material comprises about 80 wt. % PVP. In oneembodiment, the composite material comprises about 85 wt. % PVP.

In some embodiments, the composite material comprises about 0 to about30 wt. %, and preferably about 10 to about 20 wt. %. maltose. In oneembodiment, the composite material comprises about 10 wt. % maltose. Inone embodiment, the composite material comprise about 20 wt. % maltose.

In some embodiments, the composite material comprises about 0 to about20 wt. %, and preferably about 2.5 to about 10 wt. %, leucine. In oneembodiment, the composite material comprises about 2.5 wt. % leucine. Inone embodiment, the composite material comprises about 5 wt. % leucine.In one embodiment, the composite material comprises about 10 wt. %leucine.

In some embodiments, the composite material comprises about 0 to about20 wt. %, and preferably about 2.5 to about 10 wt. %, dileucine. In oneembodiment, the composite material comprises about 2.5 wt. % dileucine.In one embodiment, the composite material comprises about 5 wt. %dileucine. In one embodiment, the composite material comprises about 10wt. % dileucine.

In one embodiment the composite material comprises about 70 to about 90wt. % PVP; about 10 to 20 wt. % maltose; about 2.5 to about 10 wt. %leucine; and about 2.5 to about 10 wt. % dileucine. It has been foundthat the composite material with such combination of polymericcomponents yields microneedles 102 that have a desired durability andtensile strength to penetrate mammalian skin, and further are able toquickly dissolve upon insertion into the skin.

In one embodiment, the composite material comprises about 70 wt. % PVP;about 10 wt. % maltose; about 10 wt. % leucine; and about 10 wt. %dileucine. In one embodiment, the composite material comprises about 70wt. % PVP; about 20 wt. % maltose; about 5 wt. % leucine; and about 5wt. % dileucine. In one embodiment, the composite material comprisesabout 80 wt. % PVP; about 10 wt. % maltose; about 5 wt. % leucine; andabout 5 wt. % dileucine. In one embodiment, the composite materialcomprises about 85 wt. % PVP; about 10 wt. % maltose; about 2.5 wt. %leucine; and about 2.5 wt. % dileucine.

In some embodiments, the composite material may comprise one or moreadditional components such as chitosan. For instance, in one embodiment,the composite material may comprise PVP, chitosan, and one or morecopolymers selected from maltose, leucine, and dileucine.

In some embodiments, the composite material may exclude metallic orother polymer materials aside from PVP, maltose, leucine, and dileucine.For instance, inclusion of polyethylene glycol (PEG) into the compositematerial may make said mixture more pliable for molding purposes (e.g.,in the preparation of the microneedle structures), yet ultimately resultin microneedles that are less durable with insufficient tensile strengthto penetrate mammalian skin.

As noted above, each of the microneedles 102 comprises an agent that isreleased upon penetration and subsequent dissolution of the microneedleswithin mammalian skin. In some embodiments, the agent may comprise anactive agent. In one embodiment, the agent may comprise an antigen forfungi, bacteria, house dust, atopic dermatitis, pollen species (e.g.,cedar, cypress, ragweed, mugwort, birch, rice plants, etc.), foodspecies (e.g., eggs, tree nuts, peanuts, soy, wheat, milk, meat, rice,beans, seafood, shellfish, etc.), pet dander, textiles, detergentpreparations (e.g., laundry detergents, softeners, etc.), cosmeticpreparations, the tuberculin reaction, particular drugs, etc.

In one embodiment, the agent may comprises a cosmetic preparation.Cosmetic preparations may be formulated as lotions, creams/emulsions,lotions, ointments, pastes, suspension, powders, gels, sticks, aerosols,etc. Further, cosmetic preparations may include, but are not limited tofacial makeup preparations (e.g., rouge, eye shadow, mascara, eye liner,lipstick, lip gloss, lip liner, foundation, etc.), skin carepreparations (skin moisturize and lotion, skin cleanser, sunscreen,etc.), hair care preparations (e.g., shampoo, conditioner, leave in haircare/styling products, hairspray, hair gel, hair dyes, etc.), nail carepreparation (e.g., nail polish, nail polish remover, etc.), perfume,colognes, etc. In one embodiment, a cosmetic preparation is as definedby the FDA, and constitutes any article intended to be rubbed, poured,sprinkled, or sprayed on, introduced into, or otherwise applied to thehuman body for cleansing, beautifying, promoting attractiveness, oraltering the appearance.

In one embodiment, the agent may comprise a drug. A drug may comprises aprotein, antibody, chemical compound, DNA/RNA, etc. In one embodiment, adrug is as defined by the FDA, and constitutes any articles intended foruse in the diagnosis, cure, mitigation, treatment, or prevention ofdisease, as well as articles (other than food) intended to affect thestructure or any function of the body of man or other animals.

In one embodiment, the agent may comprise a vaccine.

In some embodiments, at least two of the microneedles 102 may comprisesthe same agent as one another. For instance, in one embodiment, at leasttwo of the microneedles 102 may comprise the same cosmetic preparation.In some embodiments, a plurality of the microneedles 102 may comprisethe same agent as one another. In some embodiments, each of themicroneedles 102 may comprise the same agent as one another.

In some embodiments, at least two of the microneedles 102 may comprisesdifferent agents as one another. For instance, in one embodiment, atleast two of the microneedles 102 may comprise different cosmeticpreparations (e.g., a makeup preparation versus a hair care preparation;different makeup preparations such as an eyeshadow versus a lipstick, ortwo different eyeshadows, etc.) In some embodiments, a plurality of themicroneedles 102 may comprise different agents as one another. In someembodiments, each of the microneedles 102 may comprise different agentsas one another.

In some embodiments, a first plurality of the microneedles 102 maycomprise a different agent from the agent associated with at least asecond plurality of the microneedles 102. For instance, with referenceto FIG. 2, at least two of the discrete areas 202 of microneedles 102may comprises different agents from one another.

In some embodiments, the concentration of the agent in each microneedleis sufficient to induce an allergic reaction but not so high as toirritate and cause a false-positive reaction in the mammalian skin towhich the agent is delivered. In some embodiments, the agent is presentin each microneedle in an amount ranging from about 0.01 wt. % to about50 wt. %. In some embodiments, each microneedle comprises a weight ratioof the agent to the composite material ranging from about 1:1 to about1:1000.

The aforementioned agent may be disposed within and/or coated on aportion of each microneedle 102 as shown in the exemplary embodiments ofFIGS. 4A-4C. In the embodiment of FIG. 4A, the agent 402 may bedispersed within the composite material of each microneedle 102. In onesuch embodiment, the agent may be uniformly dispersed within thecomposite material of each microneedle 102.

In the embodiment of FIG. 4B, the agent 402 may be coated on the entireexterior periphery of the microneedle 102. However, in alternativeembodiments, the agent 402 need not be coated on the entire periphery ofthe microneedle 102, but may be coated on one or more portions thereof.Further, the agent 402 may be uniformly dispersed within the compositematerial of each microneedle 102, as well as coated on at least aportion of the exterior periphery thereof, in some embodiments.

In the embodiments of FIG. 4C-4D, the tip portion 110 of eachmicroneedle 102 may comprise a higher concentration of the agent 402 ascompared to the base/stem portion 108 thereof. It is of note that thisconcentration gradient may arise where the base/stem portion 108 of eachmicroneedle 102 either comprises no agent 402, or comprises the agent402 at a lower concentration than the tip portion 110. Further, thisconcentration gradient may be gradual or abrupt in some embodiments.

As shown in the embodiment of FIG. 4C, the agent 402 may be dispersedpredominantly within the tip portion 110 of each microneedle 102 (e.g.,within the composite material of the tip portion 110) such that there isa larger agent 402 concentration in said tip portion 110 as compared tothe base/stem portion 108 of the microneedle 102. In such an embodiment,a majority, substantially all, or all of the agent 402 associated with amicroneedle 102 may be dispersed within the tip portion 110 of themicroneedle 102.

In the embodiment of FIG. 4D, the agent 402 may be coated predominantlyon the tip portion 110 of the microneedle 102 (e.g., coated on thecomposite material of the tip portion 110) such that there is a largeragent 402 concentration in said tip portion 110 as compared to thebase/stem portion 108 of the microneedle 102. In such an embodiment, amajority, substantially all, or all of the agent 402 associated with amicroneedle 102 may be coated on at least a portion of the exteriorsurface of the tip portion 110 of the microneedle 102. In one particularembodiment, the entire periphery of the tip portion 110 of eachmicroneedle 102 may be coated with the agent 402. In some embodiments,the agent 402 may be predominantly dispersed within the tip portion 110of each microneedle 102 (e.g., within the composite material of the tipportion 110), as well as predominantly coated on at least an exteriorsurface of said tip portion 110.

In the embodiment of FIG. 4E, each microneedle 102 may comprise aplurality of layers, where at least some of the alternating layerscomprise different concentrations of the agent 402. For instance, eachmicroneedle 102 may comprise at least three layers: a first layer 404 a,a second layer 404 b, and a third layer 404 c, where the second layer is404 b is positioned between the first and third layers 404 a, 404 c.While each of the layers may be comprised of a composite material, asdiscussed previously, the second layer 404 b may comprise a higherconcentration of the agent 402 than the first layer 404 a and/or thethird layer 404 c. In one instance, the second layer 404 b may comprisea higher concentration of the agent 402 than at least the first layer404 a. In one instance, the second layer 404 b may comprise a higherconcentration of the agent 402 than at least the third layer 404 c. Inone instance, the second layer 404 b may comprise a higher concentrationof the agent 402 than the first layer 404 a and the third layer 404 c.

Moreover, in instances where the second layer 404 b comprises a higherconcentration of the agent 402 than the first and third layers 404 a,404 c, the first layer 404 a may have the same or a different agentconcentration than the third layer 404 c. For example, the first andthird layers 404 a, 404 c may comprise equal concentrations of the agent402, which is lower than the concentration of the agent 402 in thesecond layer 404 b. Similarly, the second layer 404 b may comprise apredetermined amount of the agent 402, whereas the first and third layer404 a, 404 c comprise none, or substantially none, of the agent 402.Alternatively, the second layer 404 b may comprise a higherconcentration of the agent 402 than the first and third layers 404 a,404 c, however the first layer 404 a may comprise a higher (or lower)agent concentration than the third layer 404 c.

In other instances, the concentration of the agent 402 may decrease fromthe first layer 404 a to the third layer 404 c (e.g., the second layer404 b may comprise a lower agent concentration than the first layer 404a and a higher agent concentration than the third layer 404 c). In yetmore instances, the concentration of the agent 402 may increase from thefirst layer 404 a to the third layer 404 c (e.g., the second layer 404 bmay comprise a lower agent concentration than the third layer 404 c anda higher agent concentration than the first layer 404 a).

It is of note that the number and configuration of the layers is notlimited by the schematic of FIG. 4E. For example, in further instances,each microneedle may comprise a fourth layer adjacent the third layer404 c, and a fifth layer adjacent the fourth layer such that the fourthlayer is positioned between the third layer 404 c and the fifth layer.The fourth and fifth layer may independently comprise an agentconcentration that is the same or different than any of the otherlayers. In one exemplary instance, the second layer 404 b and the fourthlayer may each comprise an agent concentration that is higher than thefirst and third layers 404 a, 404 c. In one such instance, the agent 402may be present in the second layer 404 b and the fourth layer, yetabsent, or substantially absent, in the first and third layers 404 a,404 c.

In some embodiments, the scaffold 106 is configured to temporarily andremovably contact the outer layer of mammalian skin (e.g., the stratumcorneum) upon engagement of the microneedle patch 100 therewith, andparticularly when the microneedles 102 have pierced the skin to a depthof between 50 μm to 1000 μm (see, e.g., FIG. 3). In such embodiments,the surface 104 of the scaffold 106 to which the microneedles 102 arecoupled may contact the outer layer of the skin. Accordingly, thescaffold 104 may preferably be comprised of a flexible materialconfigured to provide adequate skin adhesion and/or stress dispersion.

In some embodiments, the scaffold 106 may comprise one or more of thesame materials as the microneedles 102. In one embodiment, the scaffold106 may comprise the same composite material as the microneedles 102.For instance, in one embodiment, the scaffold may comprisepolyvinylpyrrolidone (PVP) and one or more additional copolymersselected from the group consisting of maltose, leucine, and dileucine.In other embodiments, the scaffold 106 may comprises one or morematerials that are different than those of the microneedles 102.

In some embodiments, the microneedle patch 100 may be a monolithicstructure, such that the scaffold 106 and microneedles 102 are allcomprised of a single material, such as a composite material comprisingPVP and one or more additional copolymers selected from the groupconsisting of maltose, leucine, and dileucine. Formation of such amonolithic structure may involve combining PVP, the one or moreadditional copolymers, and an agent disclosed herein to form a mixture,and subsequently adding said mixture to a mold comprising the desiredshape of the microneedle patch 100. Such process may result in the agentbeing disposed in the scaffold 106 as well as the microneedles 102.However, the microneedle patch 100 may be formed by other processes thatresult in the agent being disposed in and/or the microneedles 102, butnot disposed in the scaffold 106.

In some embodiments, the microneedle patch 100 is not a monolithicstructure such that the scaffold 106 is formed separately and/or is aseparate component relative to the microneedles 102. In one suchembodiment, the microneedles 102 may be directly attached/coupled to thesurface 104 of the scaffold 102. In one such embodiment, themicroneedles 102 may be directly attached/coupled to the surface 104 ofthe scaffold 102, and do not extend within a central region of thescaffold 102. Moreover, in embodiments in which the microneedle patch100 is not a monolithic structure, the scaffold 106 may still compriseone or more of the same materials as the microneedles 102.Alternatively, in embodiments in which the microneedle patch 100 is nota monolithic structure, the scaffold may comprise one or more materialsthat are different from those of the microneedles 102. For instance, inone such embodiment, the agent may be localized in the microneedles 102and not present in the scaffold 106.

In some embodiments, the dimensions of the scaffold 106 (e.g., thewidth, w_(s), and/or length, l_(s)) may be tailored to a include acertain number and/or configuration of microneedles 102 for a specificapplication. Similarly, the height, h_(s), of the scaffold 106 may alsobe tailored, as would be appreciated by a skilled artisan upon readingthe present disclosure, to provide a desired level of support and/orflexibility thereto.

In some embodiments, the surface 104 of the scaffold 106 configured tocontact mammalian skin may comprise an optional coating thereon, wheresaid option coating comprises a material configured to provide suitableskin adhesion and/or stress dispersion. In one embodiment, themicroneedles 102 may be directly coupled to the optional coating. Inanother embodiment, the optional coating may substantially surround thebase of each of the microneedles 102, such that microneedles 102 aredirectly coupled to the surface 104 of the scaffold 106.

As disclosed herein, the microneedles 102 of the microneedle patch 100may be configured to pierce mammalian skin, preferably to a depth ofabout 50 μm to 1000 μm, and subsequently dissolve to release agentsdisposed therein and/or coated thereon. An allergic response to an agentmay be identified by an increase in the temperature of the subject'sskin at the location where said agent was delivered. Accordingly, in oneembodiment, determining a subject's allergic response to agentscomprised in the microneedles 102 may comprise determining whether thelocation at which each agent was delivered increases in temperature. Insome embodiments, the temperature increase may need to be at least equalto or exceed a threshold value to be identified as an allergic response.This threshold may be set based on the identity of the agents and/orcharacteristics of the subject (e.g., age, weight, etc.).

In some embodiments, the aforementioned temperature increase, and thusallergic response, may be determined by a detector operatively coupledto the microneedle patch 100. FIG. 5A provides a side view of themicroneedle patch 100, where such a detector 502 is located in thescaffold 106, according to one embodiment. The detector 502 may compriseone or more sensors, each of which is configured to measure/detect atemperature increase (i.e., the hot spots caused by an allergic responseto an agent). The one or more sensors may independently be a thermal orimage sensor. In one embodiment, each of the sensors of the detector 502may be an image sensor configured to capture infrared (IR) images.

FIG. 5B provides a top down view of the microneedle patch 100, were thedetector 502 comprises a sensor 504 above each microneedle 102,according to one embodiment. As noted above, each of the sensors 504 mayindependently be a thermal or image sensor. In one embodiment, each ofthe sensors 504 may be an IR image sensor.

In some embodiments, a detector configured to determine theaforementioned temperature increase, and thus allergic response, may beassociated with an external device, and not physically coupled to themicroneedle patch 100. In such embodiments, the external devicecomprising the detector may be brought within a predetermined proximityto the skin after application of the microneedle patch to determine thepresence of an allergic response.

EXAMPLES

Several illustrative examples for making and using microneedle patches,as disclosed herein, are described below. It is important to note thatthese illustrative examples are in no way limiting, and are provided byway of example only.

Example 1: Method of making a Microneedle Patch comprising a Pluralityof Microneedles, each Microneedle comprising an Agent Dispersed therein

A poly dimethyl siloxane (PDMS) mold, e.g., as shown in the embodimentof FIG. 6, was utilized for microneedle preparation according to thisfirst method. The mold was previously etched with stainless steelmicroneedles fabricated by laser cutting techniques.

A first mixture of PVP, maltose, leucine, and dileucine was prepared asa slurry to form the composite material of the microneedles. The weightratio of PVP to the combination of maltose, leucine, and dileucine wasabout 2:1 (PVP: maltose+leucine+dileucine=2:1) to give stability to thePVP. An agent was added to the first mixture, where the weight ratio ofthe agent to the mixture of PVP, maltose, leucine, and dileucine wasabout 1:4. ratio. Approximately 25 to 30 μl of the first mixture wasapplied to the PDMS mold and allowed to dry in a desiccator attached toa vacuum pump for about 5 to 10 mins to form the microneedles.

A second mixture of PVP, maltose, leucine, and dileucine was prepared asa slurry to form the composite material of the scaffold (or pedestal).This second mixture did not include any agent. Approximately 150 to 200μl of this second mixture was applied to the PDMS mold over thepreformed microneedles.

The mold comprising both the first and second mixtures was then driedovernight in a sterile environment at room temperature, thereby formingthe microneedle patch comprising the agent dispersed in the each of themicroneedles. An example of a microneedle patch formed via this firstmethod may be found, e.g., in FIGS. 4A and 4C.

Example 2: Method of making a Microneedle Patch comprising a Pluralityof Microneedles, each Microneedle comprising an Agent Coated on thePeriphery thereof

A poly dimethyl siloxane (PDMS) mold, e.g., as shown in the embodimentof FIG. 6, was also utilized for microneedle preparation according tothis second method. As noted above, the mold was previously etched withstainless steel microneedles fabricated by laser cutting techniques.

Approximately 10 μl of the agent was initially poured into the etchedgrooves of the PDMS mold and allowed to dry under vacuum for 3 to 5minutes in a suitable solvent. A mixture of PVP, maltose, leucine, anddileucine was then prepared as a slurry to form the composite materialof the microneedles. The weight ratio of PVP to the combination ofmaltose, leucine, and dileucine was about 2:1 (PVP:maltose+leucine+dileucine=2:1). Approximately 120 μl of the slurry wasapplied to the PDMS mold comprising the agent, and the mold was allowedto dry in a desiccator attached to a vacuum pump for about 5 to 10 minsto form the microneedles.

A second mixture of PVP, maltose, leucine, and dileucine was prepared asa slurry to form the composite material of the scaffold (or pedestal).This second mixture did not include any agent. Approximately 150 to 200μl of this second mixture was applied to the PDMS mold over thepreformed microneedles.

The mold comprising both the first and second mixtures was then driedovernight in a sterile environment at room temperature, thereby formingthe microneedle patch comprising the agent disposed on the periphery,and preferably an entire periphery, of each microneedle. The microneedlepatch formed via this second method results in rapid release of theagent upon contact with the skin unlike microneedle patches formed viathe first method, which exhibit slow and sustained release of the agent.Moreover, the microneedle patch formed via this second method comprisemicroneedles having a solid mechanical strength for the agent to betested. An example of a microneedle patch formed via this second methodmay be found, e.g., in FIGS. 4B and 4D.

Example 3: Method of making a Microneedle Patch comprising a Pluralityof Microneedles, each Microneedle comprising Layers of AlternatelyHigher and Lower Concentrations of an Agent

A poly dimethyl siloxane (PDMS) mold, e.g., as shown in the embodimentof FIG. 6, was again utilized for microneedle preparation according tothis third method. As noted above, The mold was previously etched withstainless steel microneedles fabricated by laser cutting techniques.

A first mixture of PVP, maltose, leucine, and dileucine was prepared asa slurry. The weight ratio of PVP to the combination of maltose,leucine, and dileucine was about 1:1 (PVP:maltose+leucine+dileucine=1:1). Approximately 30 μl of the first mixturewas applied to the PDMS mold to form a first layer, and allowed to dryovernight.

Approximately 10 μl of the agent to be tested was then added to the moldcomprising the dried first mixture. The newly added agent was allowed todry over night at room temperature, thereby forming a second layer.

A second mixture of PVP, maltose, leucine, and dileucine was prepared asa slurry. Each of the maltose, leucine, and dileucine were mixed withthe PVP in about a 1:1 weight ratio. Approximately 120 μl of the secondmixture was applied to PDMS mold comprising the first and second layers.

The resulting mold was then dried, thereby forming multilayeredmicroneedles having an layer comprising an agent located between twolayers of composite material which do not comprise said agent. Themicroneedle patch formed via this fourth method results resulting in asustained release of the agent.

Example 4: Method of using a Microneedle Path in a Mouse Model

To evaluate a microneedle patch, as disclosed herein, the microneedlepatch was stained with a blue dye, inserted into a 20 to 25% gelatin gel(w/v) for about 30 to 60 seconds, and removed to check the dissolutionof the microneedles and release of the agent therefrom.

The long-term agent retaining abilities of the microneedle patch weretested using in vitro release studies. The microneedle patch was brieflyimmersed into about 200 μl of physiological saline for about 30 minutes,and the released agent was quantified by analytical methods. The agentof choice to establish the agent retaining ability of the microneedlepatch was insulin, the release of which could be easily quantified byELISA (enzyme-linked immunosorbent assay).

The in vivo agent release in an animal model was studied using mice.Briefly, the mice were anesthetized using isoflurane, and their backsshaved with clippers to remove the hair. The implant site was cleanedwith povidone iodine solution to clear off the remaining hair and otherdebris. As shown in FIG. 7A, the microneedle patch 100 comprising themicroneedles and agent associated therewith was inserted into the skinof the mice under anesthesia, and the responsiveness of the skin to theagent delivered upon dissolution of the microneedles wasevaluated/captured at different time periods (see, e.g., FIGS. 7B-7D)using an infrared thermal camera 702.

The foregoing description of the present invention has been provided forthe purposes of illustration and description. It is not intended to beexhaustive or to limit the invention to the precise forms disclosed. Thebreadth and scope of the present invention should not be limited by anyof the above-described exemplary embodiments. Many modifications andvariations will be apparent to the practitioner skilled in the art. Themodifications and variations include any relevant combination of thedisclosed features. The embodiments were chosen and described in orderto best explain the principles of the invention and its practicalapplication, thereby enabling others skilled in the art to understandthe invention for various embodiments and with various modificationsthat are suited to the particular use contemplated. It is intended thatthe scope of the invention be defined by the following claims and theirequivalence.

What is claimed is:
 1. A microneedle patch comprising: a patch scaffoldhaving a surface; a plurality of microneedles disposed on the surface,wherein: each microneedle of the plurality of microneedles is capable ofpiercing skin and being associated with an agent; the plurality ofmicroneedles is arranged into at least two groups on the surface; andmicroneedles in the first group are associated with a first agent andmicroneedles in the second group are associated with a second agent; anda detector layer disposed within the patch scaffold, wherein thedetector layer includes at least two sensors configured to detectchanges in areas of the skin corresponding to the first group ofmicroneedles and the second group of microneedles upon application ofthe microneedle patch.
 2. The microneedle patch of claim 1, wherein theat least two sensors are image sensors configured to capture images ofthe areas of the skin corresponding to the first group of microneedlesand the second group of microneedles.
 3. The microneedle patch of claim2, wherein the images are infrared images.
 4. The microneedle patch ofclaim 1, wherein the at least two sensors are temperature sensorsconfigured to measure temperatures of the areas of the skincorresponding to the first group of microneedles and the second group ofmicroneedles.
 5. The microneedle patch of claim 1, wherein the at leasttwo sensors include one image sensor and one temperature sensor.
 6. Themicroneedle patch of claim 1, wherein the first agent comprises at leastone of an antigen, a cosmetic preparation, a drug, or a vaccine.
 7. Themicroneedle patch of claim 1, wherein the second agent comprises atleast one of an antigen, a cosmetic preparation, a drug, or a vaccine.8. The microneedle patch of claim 1, wherein the first agent and thesecond agent are same agents.
 9. The microneedle patch of claim 1,wherein the first agent and the second agent are different agents. 10.The microneedle patch of claim 1, further comprising: a pedestal on thesurface for adhesion to the skin.
 11. The microneedle patch of claim 1,wherein each microneedle of the plurality of microneedles is dissolvableto deliver the associated agent through the skin upon application. 12.The microneedle patch of claim 1, wherein each microneedle of theplurality of microneedles comprises a composite material comprisingpolyvinylpyrrolidone (PVP) and one or more additional copolymersselected from a group consisting of maltose, leucine, and dileucine. 13.The microneedle patch of claim 12, wherein the composite materialcomprises about 70-90 wt. % PVP.
 14. The microneedle patch of claim 12,wherein the first agent and the second agent are dispersed uniformlywithin the composite material.
 15. The microneedle patch of claim 12,wherein the first agent and the second agent are dispersed as a gradientwithin the composite material.
 16. The microneedle patch of claim 1,wherein each microneedle of the plurality of microneedles comprises aplurality of layers.
 17. The microneedle patch of claim 16, wherein eachlayer of the plurality of layers is associated with different agents.18. The microneedle patch of claim 16, wherein each layer of theplurality of layers is associated with different concentrations of asame agent.
 19. A method of determining an immune response comprising:applying the microneedle patch of claim 1 on mammalian skin; andmonitoring skin temperature to determine whether the first agent or thesecond agent of the microneedle patch of claim 1 is causing the immuneresponse.
 20. The method of claim 19, wherein the immune responsecorresponds to an increase in the skin temperature.